Feature Limited Compur Shutters

[alt.kafka]

In my collection of useless stuff that I've acquired because I didn't know better, I have two Compur 0 shutters that have fairly limited diaphragms. That is to say, at wide open, which says f/5.6, the diaphrams are substantially stopped down. One of them has no focusing lever.

What's the background on these lenses? I have to wonder whether they were originally intended for large format use, or if they have been repurposed from somewhere else - maybe some kind of a rangefinder?

[domaz]

Polaroid Copal shutters are like this too. They were designed for a specific mass production camera which didn't need a wider diaphragm or a focusing level, so they probably used a limited shutter to keep costs down.

[B.S.Kumar]

Some shutters have a small screw that limits the aperture. Remove the screw and it opens up fully.

Kumar

[Greg]

I've had shutters that the curved open "hole" that the aperture pin traveled along in limited the widest and smallest apertures. On one of these shutters. I increased the size of the curved "hole" and intern increased the widest aperture and decreased the smallest aperture. Did it very carefully with a Dremel bit and a small vacuum hose picking up the metal shavings. Shutter was clamped in an X-Y table vice under a small hobby drill press. Trick was to go really, really slowly wearing a pair of close up glasses. Took me a few tries on plain pieces of sheet metal to get the hang of it.

[alt.kafka]

Some shutters have a small screw that limits the aperture. Remove the screw and it opens up fully.

Kumar

Yeah, on one there was a pin on the ring that looked like it could be pressed out or ground off. I haven't really fiddled with it yet.


I've had shutters that the curved open "hole" that the aperture pin traveled along in limited the widest and smallest apertures. On one of these shutters. I increased the size of the curved "hole" and intern increased the widest aperture and decreased the smallest aperture. Did it very carefully with a Dremel bit and a small vacuum hose picking up the metal shavings. Shutter was clamped in an X-Y table vice under a small hobby drill press. Trick was to go really, really slowly wearing a pair of close up glasses. Took me a few tries on plain pieces of sheet metal to get the hang of it.

I forget how the range was set on the one I opened up. I think I recall just being able to remove the existing pin, and putting another in a different hole, but that something else stopped the lower range. You could see that they had a couple of different setups that could be built around the same parts.

[CatSplat]

Some Compurs had limited aperture ranges to match the lenses installed in them. I have a Synchro-Compur where the aperture only opens as wide as the pupil size of its 65/5.6 Super Angulon.

[Greg]

Some shutters have a small screw that limits the aperture. Remove the screw and it opens up fully.

Kumar

Much prefer to just increase the range that the pin can travel/move in, verses removing the pin altogether. Years ago removed the pin, and it allowed the iris to open up more. Unfortunately one time I closed down the iris and accidentally applied too much pressure, forgetting that the pin's movement was not limited anymore... The leafs in the iris never opened up evenly again.